Multiple steam jet refrigerating system



Aug. 9, 1938. J. E. HAINES MULTIPLE STEAM JET REFRIGERATING SYSTEM Filed Jan. 8, 1956 JokmEHaimes TIIPLE STEAM .lE'll REFRHGERWTIING SYMPEIW .lohn lE. Haines, Minneapolis, Minn, assignor to Minneapolis-Honeywell Regulator llompany, Minneapolis, Minn, a corporation oi llvelaware Application .llanuary t, l93t, Serial No. 58,1ll9

This invention relates to control systems for steam jet refrigerating mechanisms and more particularly to a control system for a steam jet refrigerating mechanism having a plurality of steam jet ejectors which are to be placed sequentially in operation in accordance with the load on the refrigerating mechanism or in accordance with changes in a condition.

It is an object of this invention to provide a control system for a multiple steam jet ejector mechanism whereby various of the steam jet ejectors may beplaced in operation in accordance with the load on the steam jet refrigerating mechanism or in accordance with changes in a condition. This may be accomplished by having a condition responsive device which may respond to the temperature of the cooling fluid returning to the evaporator for operating a proportioning motor. The proportioning motor may in turn operate a plurality of switching mechanisms, each of which control the supply of steam to the various steam jet ejectors, the arrangement being such that as the load on the refrigerating mechanism increases, the number of steam jet ejectors placed in operation likewise increase. The manner in which this type-f control is accomplished, and the structure for accomplishing this control also form objects of this invention.

Other objects and advantages will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawing in which drawing is diagrammatically illustrated my .control system as applied to a multiple steam jet ejector refrigerating mechanism.

Referring now to the drawing, an evaporator for chilling the cooling fluid is illustrated at it and a condenser is illustrated at i l. The evaporator ill is provided with a nozzle box it which is connected by steam jet ejectors it, it and it to a common terminal it which opens into a condenser ll. Steam is supplied to the ejectors it, ill andl5 through pipes til, it and ill, respectively, leading from some source of steam, not shown. The supply of steam through these pipes ll; l8 and i9 is controlled by valves 2t, 2t and 522, respectively, which are moved to an open or closed position by means of motors 23, 2t and 25, respectively. Since steam jet ejectors of this type are generally known in the art a detailed description thereof is not considered necessary, it being suflicient to state that as the steam jet ejectors it, it and it are placed in operation, a vacuum is created within the evaporator it to cause chillingof the cooling fluid therein. A vacuum is also maintained within the condenser ill to assist in condensing the steam utilized in the ejectors l3, M and i5 and the steam flashed in. the evaporator it. For purposes of condensing (iUl. 236-11) pended condenser water may be discharged from the condenser it by a pipe ll.

Chilled cooling fluid is drawn from the evaporator it through a pipe it by a circulating pump 29 and is delivered through a pipe ill to a point of use, not shown. The expended cooling fluid is returned from the point of use through a pipe it to a spray located withinthe evaporator it 'all of which is old in the art.

This invention contemplates the use of a proportioning motor til which may be of the type shown and described in Patent No. 1,989,972

- issued to Lewis L. Cunningham on February 5,

1935. This proportioning motor is adapted to operate a shaft it which carries spaced cams 35, it and ill. The spaced cams have high and low dwells for operating pivoted levers it, ill and ill, respectively. The levers it, it and llgcarry double ended mercury switches it, ll and it, respectively. The cams 2%, it and iii are so adjusted with respect to each other that upon clockwise rotation of shaft til, as viewed in the drawing, the mercury switch ill will first be tilted by the high dwell of cam til, then the mercury switch ll will be tilted by the high dwell of cam lit and then the mercury switch til will be tilted by the high dwell of cam t'l. Upon counterclockwise rotation of the shaft (it, the mercury switch M will first be returned to its normal position, then the mercury switch it and then the mercury switch till.

Line wires leading from some source of power, not shown, are designated at it and it. The line wire lit is connected by a wire til to the common terminal oi mercury switch it. The lefthand and right-hand electrodes of the mercury switch it are connected by wires it and it, re-- spectively, to the motor it which controls the operation of the valve lit. The motor it is also connected by wire it to the other line wire it, the arrangement being such that when the low dwell of cam it is effective, the mercury within the mercury tube til bridges the right contacts of the mercury switch to cause operation of the valve motor 23 to move the valve to a closed position. When the high dwell of cam becomes effective, the mercury in the mercury switch 39 bridges the left-hand electrodes to cause operation of the motor it to open the valve W.

In a like manner, the mercury switch ll is connected by a wire hi to the line wire it and by wires 52 and hill to the valve motor it which opens and closes the valve it. The valve motor it is connected by a wire it to the other line wires to. Also, the mercury switch it is connected by a wire 55 to the line wire. it and by wires 56 and ti to the valve motor 25 which Clockwise movement of the shaft 34 first tilts the mercury switch 39 to cause operation of the motor 23 to cause opening movement of the valve 20. Further movement of the shaft 34 in a clockwise direction causes the high dwell of cam 36 to tilt the mercury switch 4| which causes operation of the valve motor 24 to cause opening movement of the valve 2|. Still further clockwise movement of the shaft 34 causes tilting of the mercury switch 43 to cause operation of the -rnotor 25 to move the valve 22 to an open position.

Counterclockwise movement of the shaft 34 from the extreme clockwise position first causes closing of the valve 22, then of the valve 2i, and

- lastly of the valve 2!].

Power is supplied to the proportioning motor 33 by wires 60 and Si connected across the line wires 45 and 46. A condition responsive device is generally designated at 62 and may comprise a bellows 63 connected by a capillary tube 64 to a bulb 65 responding to a condition. Preferably, the bulb 65 is placed in intimate contact with the cooling fluid returning from the point of use to the evaporator, the temperature of this cooling fluid being varied in accordance with changes of load on the refrigerating mechanism. An increase in the temperature of the cooling fluid returning to the evaporator indicates an increase in load onthe refrigerating mechanism and a decrease in temperature indicates a decrease in load on the refrigerating mechanism. The bellows 63 is adapted to operate a slider 66 with respect to a potentiometer coil 61. The slider 66 is connected by a wire 63 to the proportioning motor 33 and the ends of the potentiometer coil 61 are connected by wires 59 and 10 to the proportioning motor 33. Upon an increase in the tension of the cooling fluid returning to evaporator lll, the bellows 63 is expanded to move the slider 66 upwardly with respect to the potentiometer coil 61. This causes operation of the proportioning motor 33 to move the shaft 34 in a clockwise direction, the amount of clockwise movement of the shaft 34 being dependent upon the increase in the cooling fluid temperature. Upon a decrease in cooling fluid temperature,- the bellows 63 contracts to move the slider 66 downwardly with respect to the potentiometer coil 6?. This downward movement causes operation of the proportioning motor 33 to move the shaft 34 in a counter-clockwise direction, the amount of counter-clockwise movement being dependent upon the decrease in the temperature of the cooling fluid returning to evaporator [0. Therefore, it is seen that the proportioning motor is positioned in accordance with changes in temperature in the cooling fluid leading to the evaporator IO and consequently, in proportion to changes in the load on the refrigerating system as awhole. It is therefore seen that as the temperature increases, first the steam jet ejector. i3 is placed in operation, then the ejector M, then the ejector l5 and as the temperature of the cooling fluid decreases, first the ejector i5 is placed out of operation, then the ejector i4, and then the ejector l3, the number of ejectors in operation being proportional to theload on the' refrigerating mechanism as a whole. Ihe speciflc manner in which the proportioning motor 33 is positioned is shown (Land described in detail in the above referred to unningham patent and therefore a complete description is not consid- I this condition responsive device may respond to any condition which it is desirable to have control the steam jet refrigerating mechanism disclosed in this application.

Although I have shown for purposes of illustration one form of my invention, other forms thereof may become apparent to those skilled in the art and consequently this invention is to be limited only by the scope of the appended claims and the prior art.

I claim:

1. In a refrigerating system having an evaporator, a condenser and a plurality of ejectors, the combination of means for circulating cooling fluid to and from the evaporator, a steam valve for each ejector for controlling the supply of steam to the ejector, an electric motor for each valve for opening and closing the same, a switching means electrically connected to each motor for controlling the operation thereof, a proportioning motor for operating successively each switching means, thermostatic means responsive to the temperature of the cooling fluid returning to the evaporator, and variable resistance means operatively connected to the proportioning motor and adjusted by said thermostatic means to variably position said proportioning motor whereby the steam valves are opened successively in accordance with the load on the refrigerating system.

2. In a refrigerating system having an evaporator, a condenser and a plurality of ejectors, the combination of a steam valve for each ejector, an electric motor for each valve for opening and closing the same, a switching means electrically connected to each motor, a proportioning motor for operating successively each switching means, thermostatic means, and variable resistance means operatively connected to the proportioning motor and adjusted by said thermostatic means to variably position said proportioning motor whereby various of the steam'valves are opened in accordance with changes in temperature.

3. In a refrigeration systemghaving an evaporator, a condenser, and a plurality of ejectors, the combination of a steam valve aor controlling the flow of steam to each ejector, an electric motor for each valve for opening and closing the same, a switching means electrically connected to each valve motor, a reversible electric motor means having an operating shaft, a thermostat for controlling said reversible electric motor means, said thermostat and said motor means being arranged for varying the angular position of said operating shaft in accordance with the cooling load on the system in a manner to provide different angular positions of said operating shaft for different values of said cooling load, and

means actuated by said operating shaft for sequentially actuating said switching means, to thereby vary the number of ejectors in operation in accordance with the cooling load on the system.

JOHN E. HAYNES. 

